The invention relates to the field of electrical insulators, and in particular to the field of electrical insulators for power cables known as optical phase conductors (OPPCs). The invention also relates to the field of systems associating an electrical insulator with at least one phase conductor. This type of electrical insulator serves to pass an optical signal from one end to the other of said electrical insulator while providing electrical insulation between the ends of said electrical insulator. This type of electrical insulator serves in particular to make an optical connection between the phase conductors of the overhead electricity network and the underground optical network. Because of the great voltage difference between the overhead electricity network and the underground optical network, electrical insulation needs to be particularly good and reliable. Electrical insulators are conventionally placed at the tops of pylons supporting phase conductors. The optical fibers contained in phase conductors are connected to the underground optical network via an optical cable referred to as a “optical microcable” connecting the phase conductor to the cable of the underground optical network. The interface between the optical microcable and the phase conductor takes place via a cassette for storing splices between optical fibers situated in the electrical insulator and the interface between the optical microcable and the cable of the underground optical network is implemented via an optical connection terminal.
From prior art described in U.S. Pat. No. 5,637,827 (see FIG. 7 and lines 1 to 40 in column 7), an electrical insulator is known constituted by a dielectric covering itself constituted by a stack of skirts or “sheds” stacked one on another and stuck to one another and onto a dielectric rod which they surround. The dielectric rod presents a slot in which there is received a plastics tube for protecting an optical fiber cable, a filler material filling the interstices between the tube and the rod, and also between the tube and the cable.
In order to achieve good electrical insulation while enabling high quality optical transmission, the electrical insulator of the invention must present a good compromise between the following two properties: firstly reliable electrical insulation between opposite ends of the electrical insulator in order to ensure good electrical insulation; and secondly high-quality protection of the optical fiber cable in order to ensure good-quality optical transmission. Unfortunately, those two properties can present requirements that are contradictory, a priori. Whereas reliable electrical insulation requires as few elements as possible within the electrical insulator and as few interfaces as possible between said elements, high-quality protection for an optical fiber cable would appear, on the contrary, to require additional protection elements. Both quality of electrical insulation and quality of optical fiber cable protection require good protection for the dielectric rod surrounding the optical fiber cable.
In the above-mentioned prior art, the optical fiber cable is properly protected, but the reliability of the electrical insulation provided by the electrical insulator is insufficient. In order to improve the compromise between the reliability of the electrical insulation provided by the electrical insulator and the quality of protection provided to the optical fiber cable, one of the innovations of the invention consists in omitting the tube for protecting the optical fiber cable. Several advantageous embodiments without said protective tube achieve better compromises than in the above-mentioned prior art.